December 31 is the hard close of the remedial amendment period for most individually designed and pre-approved qualified retirement plans. Required SECURE Act, CARES Act, and SECURE 2.0 amendment language must be signed into the plan document by that date, not started, not drafted, signed. December 31 is also a plan-year boundary that triggers a cluster of other deadlines involving contribution timing, required minimum distribution start dates, and plan establishment rules. Specific dates shift year to year and should be confirmed for the current tax year.
Table of Contents
- What retirement plan deadline actually falls on December 31, 2026?
- Which plans does the December 31, 2026 amendment deadline apply to?
- What happens if the plan amendments are not signed by December 31?
- What should a plan sponsor do between now and December 31, 2026?
- Is December 31 also the deadline to set up a 401(k) plan?
- Can 401(k) contributions be made after December 31?
- How does the December 31 plan year interact with Form 5500 and other filings?
- Who can untangle a multi-state plan and filing mess before the deadline?
- Key Takeaways
- References
What retirement plan deadline actually falls on December 31, 2026?
The remedial amendment period for amendments reflecting the SECURE Act of 2019, the CARES Act of 2020, SECURE 2.0 of 2022, and related federal guidance closes December 31, 2026 for most plans, according to Dykema.
A remedial amendment period is the window the IRS gives a plan to adopt required document changes retroactively without breaking its qualified status. The plan can operate under the new rules before the document catches up, but the document must eventually match the law.
The December 31, 2026 date is a document deadline, not a contribution or filing deadline. The two get conflated constantly. Collectively bargained plans generally have until December 31, 2028, and governmental plans generally have until December 31, 2029, according to Nelson Mullins.
Which plans does the December 31, 2026 amendment deadline apply to?
The December 31, 2026 amendment deadline applies to tax-qualified retirement plans, including 401(k), profit sharing, and defined benefit plans that use the calendar year as their plan year, according to Dykema.
The required changes are substantive, not cosmetic. The SECURE Act of 2019 raised the required minimum distribution age and expanded eligibility for long-term part-time employees. The CARES Act of 2020 temporarily permitted coronavirus-related distributions and expanded plan loan options. SECURE 2.0 of 2022 added Roth catch-up contribution requirements for certain higher earners, expanded automatic enrollment provisions, raised catch-up limits for participants ages 60 through 63, and permitted pension-linked emergency savings accounts, according to Dykema.
Plans that do not use the calendar year should confirm their own remedial amendment period rather than assume December 31 applies. Deadline dates shift year to year and should be confirmed for the current tax year.
What happens if the plan amendments are not signed by December 31?
The plan may need to correct the failure through the IRS Employee Plans Compliance Resolution System, or EPCRS, according to Dykema. EPCRS is the IRS's formal correction program for retirement plan document and operational failures.
Correction is possible but adds cost, time, and paperwork that a signed amendment would have avoided. The work is the same. The path is longer.
In this scenario, the plan document is what is out of compliance, not the plan's operations. A plan can be operating correctly under the new rules while its governing document still says something outdated. The December 31 deadline exists to close that gap.
What should a plan sponsor do between now and December 31, 2026?
Work backward from the deadline. Schedule a review with legal counsel and plan service providers by October 1, 2026, according to Dykema.
Review and approve draft amendment language by November 15, 2026. Execute final amendments and distribute copies to service providers by December 11, 2026. That leaves a buffer before the December 31 close.
Assign one owner internally so the amendment does not stall between advisors. The calendar is the easy part. The hard part is making sure someone is accountable for each step.
Is December 31 also the deadline to set up a 401(k) plan?
No. For a sole proprietor or an entity taxed as a partnership or S corporation, a qualified plan can generally be established retroactively for the prior tax year by the due date of the sponsor's federal income tax return, extendable if the return is extended, according to FuturePlan.
The December 31 plan-year boundary governs the plan's own year. The establishment deadline is a separate rule tied to the sponsor's tax return.
Establishment rules differ by entity type. A C corporation, a partnership, and a sole proprietor can face different timing. Confirm the rule for the current tax year before assuming a retroactive establishment is available.
Can 401(k) contributions be made after December 31?
Employee deferrals come out of payroll, so they stop with the final payroll of the plan year. They cannot be deposited after the year closes for that year's deferral limit.
Employer contributions, such as match or profit sharing, follow different timing rules tied to the sponsor's tax return due date, including extensions. Excess deferrals above the IRC section 402(g) limit must be corrected by April 15, according to FuturePlan.
The specific dates shift year to year and should be confirmed for the current tax year. The distinction that matters is between employee money, which is payroll-driven, and employer money, which is tax-return-driven.
How does the December 31 plan year interact with Form 5500 and other filings?
Form 5500 is the annual return most qualified plans file. The calendar-year deadline is not December 31. It falls in the following year, and Form 5558 is the extension request that pushes it out further, according to FuturePlan.
Other calendar-year-adjacent dates worth knowing: February 15 for participant fee disclosures and benefit statements, March 16 for corrective distributions on failed ADP/ACP tests, and April 1 for first required minimum distributions for participants born in 1952, according to FuturePlan.
Treat December 31 as the start of a filing chain, not a single event. The plan year closes, and then the reporting, testing, and correction deadlines begin.
Who can untangle a multi-state plan and filing mess before the deadline?
When a business operates across state lines, the plan document deadline and the state filing picture tend to surface together. Nexus, payroll withholding, and entity registrations all sit in the same pile as the retirement plan amendment calendar.
Spencer Accounting Group handles Sales Tax Resolution, Back Tax Return Filing, bookkeeping, and Tax Filing for owners who are behind and want the work sequenced rather than scrambled. The firm is 100% virtual and serves clients from anywhere.
This article is general information, not tax advice for a specific situation. Book a consultation to see if Spencer Accounting Group is a fit for the retirement plan and state filing work in front of you.
Key Takeaways
- The remedial amendment period for SECURE Act, CARES Act, and SECURE 2.0 changes closes December 31, 2026 for most plans.
- Collectively bargained plans generally have until December 31, 2028, and governmental plans generally until December 31, 2029.
- Missing the amendment deadline can require correction through the IRS Employee Plans Compliance Resolution System, or EPCRS.
- A practical internal calendar works backward from December 31: review by October 1, 2026, approve language by November 15, 2026, execute by December 11, 2026.
- A qualified plan can generally be established retroactively for the prior tax year by the sponsor's tax return due date, which is a different deadline than December 31.
- Employee deferrals cannot be deposited after the plan year closes, but employer contributions follow the sponsor's tax return timing.
- Form 5500 is not due December 31; it falls in the following year, with Form 5558 available to request an extension.